Liquid crystal displays (LCDs) are display devices that use light modulating properties of crystal liquids. As the crystal liquids do not emit light directly, the LCDs require a surface light source to evenly illuminate an entire surface of a panel or screen. Backlighting is a well-known example of a surface light source technology, and thus, a backlight system is typically used for such an LCD. Light-emitting diodes (LEDs) and cold cathode fluorescent lamps (CCFLs) are examples of light sources used for backlight systems.
There are two types of backlight systems depending on the position where such a light source is arranged: edge-light type backlight systems and direct type backlight systems. In the edge-light type backlight system, light sources are arranged on a side surface of a light guide plate. On the other hand, in the direct type backlight system, light sources are arranged directly below a liquid crystal panel. Further, dimming is performed over the light sources in a backlight system using, for example, a local dimming technique. The local dimming technique refers to a technique of dividing a light exit surface of a backlight system into a plurality of areas and then performing light-intensity control for each of the areas.